1. Field of the Invention
This invention relates to a memory cell driver and, in particular, a memory cell and driver circuit using semiconductor devices.
2. Cross References-Prior Art
There are many known memory cells including several which utilize integrated circuit techniques. Typical memory cells are shown and described in U.S. Pat. Nos. 3,581,292 to Polkinghorn; 3,576,571 to Booher and 3,744,037 to Spence. However, most of the existing or known memory cell devices and associated drivers are utilized with a portion of an integrated circuit, per se. These circuits generally operate in a serial fashion, i.e. output signals are generated on appropriate addressing of the individual cells. The instant circuit, however, is directed to a memory cell device which has driver and output buffering. Thus, information generated by a suitable source such as calculator circuitry (e.g. a one chip calculator) can be utilized to drive a suitable printer device. The printer devices which can be driven include thermal print heads, solenoid driven hammer type printers or the like.
In one application, the memory cell driver with buffering is used to control the operation of a drum printer. Typical drum printers utilize one or more rotating wheels on the surfaces of which are embossed all of the alpha-numeric characters which may be printed. A separate column of characters is required for each character to be printed. The separate columns may be on a single drum or represented by a plurality of individual wheels which rotate together. The particular character which is printed is a function of the wheel position relative to time. This relationship is determined by the calculator circuitry whereby, during a particular time period, a print command is generated. The print command actuates suitable solenoids or the like wherein hammer action occurs such that a recording medium (e.g. paper) is pressed against the rotating character medium (e.g. drum or wheel) whereby the selected character is printed.
The circuit which is described herein is an interface circuit between the utilization device (i.e. printer) and the overall system (e.g. calculator chip). This interface system which includes a memory cell, drivers, and buffering output circuits, permits a single calculator chip to control a desirable utilization device.